Dart: Runs dartanalyzer for the dart_pkg build rule.

mojo/dart/mojom/BUILD.gn

Index: mojo/dart/mojom/BUILD.gn
diff --git a/mojo/dart/mojom/BUILD.gn b/mojo/dart/mojom/BUILD.gn
index ac7e2bcbe36ebb3eebbf0685d096150fc5a52af6..0c435bb457dc770ffc2c394e08005302e06d1aa9 100644
--- a/mojo/dart/mojom/BUILD.gn
+++ b/mojo/dart/mojom/BUILD.gn
@@ -5,10 +5,14 @@
 import("//mojo/public/dart/rules.gni")
 
 dart_pkg("mojom") {
+  entrypoints = [ "lib/generate.dart" ]
   sources = [
     "CHANGELOG.md",
     "README.md",
-    "lib/generate.dart",
+    "lib/src/utils.dart",
     "pubspec.yaml",
   ]
+  deps = [
+    "//third_party/dart-pkg",
+  ]
 }